The Liquid Crystal Display (LCD) is a common electronic device, and possesses properties of low power consumption, small volume and light weight. Therefore, it has been favored by the users. The Liquid Crystal Display comprises a liquid crystal display panel and a backlight module. The backlight module is located close to the liquid crystal display panel and employed to provide an area light source for the liquid crystal display panel. Generally, the backlight module comprises a light source and a light guide plate. The light emitted from the light source enters the light guide plate through the incident surface of the light guide plate. After being diffused with the light guide plate, the light exits through the illuminating surface of the light guide plate and provides an area light source for the liquid crystal display panel. The quantum dots can be utilized to emit spectrally concentrated, very pure mono lights for achieving the better image colors. Therefore, it is considered to surpass the traditional phosphor property and possible to be applied in the backlight module. At present, the quantum dot application in the backlight module can be a quantum dot film. Generally, the quantum dot film is cut and applied in the backlight module. However, the unstability of the quantum dots, the edge of the quantum dot film in a certain range (such as, about 1 mm) after being cut can easily react with the oxygen or water vapor in the air. Consequently, the edge can fail after the quantum dot film is cut. The quality of the light emitted from the edge of the quantum dot film after being cut is affected. Moreover, the performance of the display image of the liquid crystal display device is influenced.